Clinical implications of MRI classification and analysis of prognostic risk factors in anti-NMDAR encephalitis

ObjectiveTo compare the clinical characteristics between magnetic resonance imaging (MRI)-positive and MRI-negative patients with anti-N-methyl-D-aspartate receptor (NMDAR) encephalitis, analyze the distinct clinical features of the MRI-negative group during the acute phase, and develop a prognostic prediction model based on follow-up data.MethodsA total of 112 patients with first-episode anti-NMDAR encephalitis admitted to the First Affiliated Hospital of Nanchang University between August 2019 and August 2024 were retrospectively enrolled. Based on the presence or absence of causative lesions on the initial cranial MRI performed during the acute phase (within 30 days of onset), patients were categorized into MRI-positive and MRI-negative groups. Prognosis was assessed using the modified Rankin Scale (mRS), with a score of ≥3 defining a poor outcome. Binary logistic regression was employed to screen for prognostic risk factors.ResultsIn the comparison between the MRI-negative and MRI-positive groups during the acute phase, patients in the positive group were older, had a higher incidence of prodromal symptoms, and exhibited a longer interval from onset to immunotherapy (PPOR=3.47, 95%CI: 1.41-8.55) and impaired consciousness (OR=4.00, 95%CI: 1.69-9.45) were associated with an increased risk of poor prognosis. An elevated neutrophil-to-lymphocyte ratio (NLR) was also identified as an independent risk factor (OR=1.20, 95%CI: 1.05-1.38). Elevated platelet levels (OR=0.98, 95%CI: 0.988-0.999) and albumin levels (OR=0.88, 95%CI: 0.79-0.98) were protective factors.ConclusionPatients with MRI-negative NMDAR encephalitis in the acute phase present with distinct clinical and laboratory features. However, MRI findings are not directly associated with prognosis. Relapse, neurological deficits, hematological abnormalities, and electroencephalogram changes serve as key indicators for prognosis evaluation.